There are a number of U.S. patents that disclose electronic apparatus for printing indicia on labels, some are restricted to handheld units and others disclose desktop units. Labeling machines are disclosed, for example in U.S. Pat. Nos. 4,497,682, Hamisch; 4,498,947, Hamisch; 4,501,224, Shibayama; 4,511,422, Hamisch; 4,544,434, Mistyurik; 4,556,442, Torbeck; 4,584,048, Hamisch; 4,630,538, Cushman; 4,680,078, Vanderpool; 4,807,177, Ward; 5,015,324, Goodwin; 5,078,523, McGourty; 5,372,443, Borucki; 5,494,365, Nagae; 5,516,219, Leonard; 5,672,020, Leonard; 5,918,989, Stout; 5,318,370, Nehowig and 6,644,876, Carriere. Various general purpose label printers are described in the following: U.S. Pat. Nos. 4,440,248, Teraoka; 4,501,224, Shibayama; 4,630,538, Cushman; and 4,655,129, Wirth.
The electronic machines for printing labels of the type disclosed above include the same general combination of elements; a print head, a means for feeding labeling media past the print head, a microprocessor, a read only memory programmed with appropriate instructions to operate a microprocessor, a random access memory, a keyboard with letter, number and function keys for the entry of alphanumeric information and instructions concerning the indicia to be printed, and a visual display device such as an LED, LCD or other graphic display unit to assist the operator in using the machine.
Thermal transfer or direct thermal printing uses a heat generating print head to transfer a pigment, such as wax, carbon black, or the like, from a thermal transfer ribbon onto a labeling media such as a vinyl tape supply and/or heat the print media. By using digital technology, characters, symbols or shapes are formed upon energizing a sequence of pins on the print head which in turn melt the wax or other pigment on the ribbon transferring the image to the labeling media supply and/or heat the print media.
The labeling media supply comprises either a continuous strip, a laser die cut series of labels attached to a carrier strip or other similar format. The labels are then removed from the carrier and attached to the objects needing identification. As there are many types of labeling applications, there are many combinations of labels and carrier strips that provide labels of varying sizes, colors, and formats. Many label printers are designed for printing on label media that meets certain physical criteria for end use. An operator has no way of reliably knowing whether the labeling media is compatible with the particular printer and if it meets the printer manufacturer's operating specifications. A mismatch between the labeling media and the print head's energy level within the printing apparatus may result in poor print quality or even damage to the printing apparatus.
Methods are known in the art that address the problem of using incompatible labeling media. One approach is to provide an adjustable platen for a label printer which accommodates media of widely different widths and thicknesses as disclosed by U.S. Pat. No. 5,372,443, Borucki et al. These mechanical measures are not helpful in differentiating print media designed for use in thermal printers. In U.S. Pat. No. 5,318,370, Nehowig teaches a thermal printing machine with a tape cassette including a memory circuit with two separate memory areas where an algorithm provides validation. The present invention removes the unnecessary step of requiring an algorithm to encrypt, encode, decode and decrypt a test number pattern using two memory locations to determine a cartridge's validity. In U.S. Pat. No. 5,918,989, Stout teaches a handheld labeler where a spool contains a memory chip which stores information about the print media where this information is conveyed to the printer through concentric electrical contacts on the end of the spool. The concentric electrical contacts engage stationary contacts on the printer wherein the electrical contact connection is insensitive to incidental rotation. The present invention does not necessitate any concentric or any other specific type of electrical contact connector. In U.S. Pat. No. 6,644,876, Carriere teaches a method and apparatus for printer cartridge identification where the identification circuit is triggered by an electrical connection between a printed circuit board coupled to the cartridge and a plurality of spring contacts in a cartridge receptacle in the printer. The present invention does not require or use spring contacts which may suffer from both expense or premature wear and fatigue of springs at the point of insertion.